Ultrasound-assisted magnetic solid phase extraction of lead and thallium in complex environmental samples using magnetic multi-walled carbon nanotubes/zeolite nanocomposite

Magnetic multi-walled carbon nanotubes@zeolite (MWCNT-Fe₃O₄@Zeo)nanocomposite was facilely synthesized using a one-pot solvothermal method. The MWCNT-Fe₃O₄@Zeo was characterized by VSM, BET, XRD, TEM and SEM/EDS. The Zeolite-coated multi-walled carbon nanotubes–magnetite was used as an adsorbent in ultrasonic-assisted magnetic solid phase extraction (UA-MSPE)for preconcentration of trace Pb and Tl. The analytes were detected and quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). The optimization of experimental parameters affecting the preconcentration method was achieved using a multivariate approach. Under optimal experimental conditions, the linearity ranged from 0.1 to 500 μg L⁻¹ for lead and 0.1–600 μg L⁻¹ for thallium. Preconcentration factors, limits of detection and quantification for Pb and Tl ranged from 90 to 100, 0.28–0.23 μg L⁻¹, 0.93–0.77 μg L⁻¹. The intraday precisions (repeatability, n = 20)expressed as the relative standard deviation, were found to be 1.6% and 1.4% for Pb and Tl, respectively. In addition, the interday precisions (reproducibility, n = 5)were 2.6% and 3.1% for Pb and Tl, respectively. The accuracy of the method was investigated using standard reference material as well as spiked recovery test and satisfactory recoveries (97–99.3%)were obtained. The maximum adsorption capacities were 37.8 mg g⁻¹ and 44.5 mg g⁻¹, for Pb and Tl, respectively. The developed UA-MSPE/ICP-OES method was effectively applied for simultaneous preconcentration and determination of Pb and Tl in environmental samples.